1. Field of the Invention
The present invention relates to semiconductor manufacturing facilities and, more particularly, to a semiconductor manufacturing facility including an apparatus that generates vibration such as a scan-type exposure apparatus, which applies an exposure process to a semiconductor wafer, and a semiconductor manufacturing method performed by such a semiconductor manufacturing facility.
2. Description of the Related Art
In order to raise a manufacturing efficiency in a semiconductor manufacturing process, a diameter of a semiconductor wafer tends to increase and is presently shifting from a wafer with a diameter of 200 mm (8 inches) to a wafer with a diameter of 300 mm (12 inches). In connection with such a shift in the semiconductor wafer, semiconductor manufacturing apparatuses and semiconductor manufacturing facilities are also becoming large-scaled.
For example, a scan-type exposure apparatus handling a wafer with a diameter of 300 mm in a lithography apparatus is provided with a mechanism for moving a stage on which a light-source is provided, in addition to a mechanism for moving a wafer stage on which a wafer to be processed is placed. For this reason, the scan-type exposure apparatus handling the wafer with a diameter of 300 mm has a weight as heavy as 9.5 tons. Therefore, an installation floor of a clean room on which such a heavyweight scan-type exposure apparatus is installed requires an increased withstand load. Although the scan-type exposure apparatus has a precise moving mechanism and must be made so that vibration is not transmitted thereto from outside, the apparatus itself is a source of vibration since the apparatus has a mechanism that intermittently moves the stages.
The conditions of installation of the above-mentioned scan-type exposure apparatus have mainly been established according to a request from manufacturers of the apparatus. That is, it is required by the manufacturers of a scan-type exposure apparatus that the conditions of the following items should be satisfied with respect to a weight and vibration characteristic of the installation floor.
(1) Acceleration of vibration in ⅓ octave-band peak-hold analysis O-P value
(2) Acceleration of vibration (O-P) value in a time history waveform
(3) Target accelerance of an installation floor of an exposure apparatus
In order to satisfy such vibration conditions, it is general to provide an installation table or stand on an installation floor of a clean room so as to install a scan-type exposure apparatus on the installation table. As for the installation table, there is an approach of interrupting transmission of vibration by rigidity and weight of concrete. There also is an approach using an anti-vibration table, which prevents transmission of vibration by a damping mechanism incorporated in the installation table.
However, a weight of a concrete installation table, which satisfies vibration conditions required by the scan-type exposure apparatus handling the wafer with a diameter of 300 mm, is as large as 11 tons, and becomes about 20 tons if when the weight of the apparatus itself is added. Therefore, the installation floor of the clean room must be so designed and constructed to withstand such a large load.
Generally, the installation floor of a clean room consists of slabs supported by columns. However, in order to make the installation floor supporting a weight of about 20 tons, the number of columns must be increased very much and such a floor may not be designed by a conventional design method. Moreover, once the concrete installation table is constructed, it is difficult to move the installed position thereof. Accordingly, the concrete installation table gives less freedom of an installation position of the apparatus in the clean room. Therefore, there is a problem in that a layout of apparatuses in a clean room cannot be changed.
Thus, there is a case in which an anti-vibration table is used instead of the concrete installation table. FIG. 1 is an illustrative view of a conventional installation construction of a lithography apparatus. The lithography apparatus shown in FIG. 1 has a scan-type exposure apparatus 10 and a coater/developer apparatus 12. The scan-type exposure apparatus 10 has a very large weight, and generates vibration during operation. A laser light for exposure is supplied to the scan-type exposure apparatus 10 from a laser oscillator 14.
The scan-type exposure apparatus 10 is installed on an anti-vibration table 16 so that vibration generated by the apparatus 10 is not transmitted to other apparatuses. The anti-vibration table 16 is also referred to as an active vibration-eliminating table, and is provided with a damping device. That is, the anti-vibration table 16 does not only prevent vibration from being transmitted to the scan-type exposure apparatus 10 but also has a special mechanism to interrupt vibration generated by the apparatus itself so that the vibration is not transmitted outside. The anti-vibration table 16 is installed on an installation floor 18 of a clean room.
A coater/developer apparatus 12 and a laser oscillator 14 are installed on a free access floor panel 20, which is provided on the installation floor 18 of the clean room. Although the anti-vibration table 16 and the free access floor panel 20 are arranged on the same installation floor 18, they are separated from each other and do not contact to each other. The installation floor 18 consists of slabs each of which is supported by a plurality of columns 22 from the bottom side. Since the scan-type exposure apparatus 10 is very heavy and is arranged on the anti-vibration table 16, the number of columns must be increased so that the installation floor withstands such a weight and vibration is not transmitted thereto.
Considering layout change of apparatuses in a clean room, it is desirable to make the installation floor 18 a uniform configuration, and, thereby, the columns 22, which support the installation floor 18, are arranged at a uniform interval. That is, the interval D of the column 22 supporting the installation floor 18 of the clean room is determined by an interval required for a part where the scan-type exposure apparatus 10 and the anti-vibration table 16 are arranged, and, thus, the columns 22 must be located at a very small interval over the entire clean room. Therefore, The installation floor has an excessive withstand load in parts other than the part where the scan-type exposure apparatus 10 is installed. Moreover, the anti-vibration table 16 per se becomes very heavy since the special damping device is provided, and the structure thereof also becomes complicated.
Moreover, even when the above-mentioned anti-vibration table 16 is used, the summed weight of the scan-type exposure apparatus 10 and the anti-vibration table 16 is very large. Therefore, according to a conventional design approach, the interval D between the columns 22 must be decreased to about 3.5 m. However, if the interval D of the columns 22 becomes small, a new problem may arise. Generally, devices (accessories) relevant to an apparatus installed on a part of the installation floor 18 directly above the devices are located underneath the installation floor 18. However, if the interval D of the columns 22 is decreased, a space where the accessories are located is also decreased, and, thereby, the accessories cannot be accommodated within a predetermined range. That is, there is a problem in that the accessories to be provided under the installation floor 18 cannot be arranged well although various apparatuses can be arranged in the clean room.